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Last active December 15, 2020 14:15
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HMAC signature calculation: command line example
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HMAC_cmd_line.md

Example of how to calculate an HMAC signature using command line utilities:

echo -n "/path/subscribe?account_id=my_account&club_id=club%20id&msisdn=27820000000&timestamp=2012-05-29T15%3A00%3A12Z" | openssl dgst -sha256 -hmac "secret_value" -binary | base64
@derricksimpson
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This is very handy! I stumbled upon this, and tried it out for a use-case I was working with. I discovered that the quotes around secret_value were also getting interpreted as part of the secret value.

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cobusc commented Dec 15, 2020

This is very handy! I stumbled upon this, and tried it out for a use-case I was working with. I discovered that the quotes around secret_value were also getting interpreted as part of the secret value.

@derricksimpson Thanks for pointing that out. I have changed the quotes to be normal ASCII double quotes, in which case it works fine:

echo -n "/path/subscribe?account_id=my_account&club_id=club%20id&msisdn=27820000000&timestamp=2012-05-29T15%3A00%3A12Z" | openssl dgst -sha256 -hmac "secret_value" -binary | base64   

PuNpNuWU4//lwwRb+Cs4T48/J0/za1V4KsbU85ScTnI=

and

echo -n "/path/subscribe?account_id=my_account&club_id=club%20id&msisdn=27820000000&timestamp=2012-05-29T15%3A00%3A12Z" | openssl dgst -sha256 -hmac secret_value -binary | base64   

PuNpNuWU4//lwwRb+Cs4T48/J0/za1V4KsbU85ScTnI=

returns the same value.

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